<?php

/**
 * Class FinderPattern
 *
 * @created      17.01.2021
 *
 * @author       ZXing Authors
 * @author       Smiley <smiley@chillerlan.net>
 * @copyright    2021 Smiley
 * @license      Apache-2.0
 */
declare(strict_types=1);

namespace zxf\QrCode\Detector;

use function sqrt;

/**
 * Encapsulates a finder pattern, which are the three square patterns found in
 * the corners of QR Codes. It also encapsulates a count of similar finder patterns,
 * as a convenience to the finder's bookkeeping.
 *
 * @author Sean Owen
 */
final class FinderPattern extends ResultPoint
{
    private int $count;

    public function __construct(float $posX, float $posY, float $estimatedModuleSize, ?int $count = null)
    {
        parent::__construct($posX, $posY, $estimatedModuleSize);

        $this->count = ($count ?? 1);
    }

    public function getCount(): int
    {
        return $this->count;
    }

    /**
     * @param  \zxf\QrCode\Detector\FinderPattern  $b  second pattern
     * @return float distance between two points
     */
    public function getDistance(FinderPattern $b): float
    {
        return self::distance($this->x, $this->y, $b->x, $b->y);
    }

    /**
     * Get square of distance between a and b.
     */
    public function getSquaredDistance(FinderPattern $b): float
    {
        return self::squaredDistance($this->x, $this->y, $b->x, $b->y);
    }

    /**
     * Combines this object's current estimate of a finder pattern position and module size
     * with a new estimate. It returns a new FinderPattern containing a weighted average
     * based on count.
     */
    public function combineEstimate(float $i, float $j, float $newModuleSize): static
    {
        $combinedCount = ($this->count + 1);

        return new self(
            ($this->count * $this->x + $j) / $combinedCount,
            ($this->count * $this->y + $i) / $combinedCount,
            ($this->count * $this->estimatedModuleSize + $newModuleSize) / $combinedCount,
            $combinedCount,
        );
    }

    private static function squaredDistance(float $aX, float $aY, float $bX, float $bY): float
    {
        $xDiff = ($aX - $bX);
        $yDiff = ($aY - $bY);

        return $xDiff * $xDiff + $yDiff * $yDiff;
    }

    public static function distance(float $aX, float $aY, float $bX, float $bY): float
    {
        return sqrt(self::squaredDistance($aX, $aY, $bX, $bY));
    }
}
